1. Field of the Invention
The subject invention generally pertains to centrifugal fans and more specifically to flow measuring systems for such fans.
2. Description of Related Art
The volume of air flowing through a fan can be difficult to determine because the air velocity usually varies depending on the location of the air streams within the fan or within the ducts leading to or from the fan. In some cases, a series of pressure taps distributed across the flow path provides a means for integrating the air's velocity profile, from which the total airflow volume can be determined. Inserting such pressure taps across the flow path, however, can disrupt and restrict the flow.
In other cases, the air is directed through a certain flow restriction for which there is a known relationship between the volume airflow rate and the resulting pressure drop across the restriction. Such an approach, however, can present an undesirable flow restriction and requires multiple pressure taps to sense the pressure drop across the restriction.